Recently, n-type Mg₃Sb_1.5Bi_0.5-based thermoelectric materials have attracted considerable attention for their extraordinary thermoelectric performance. Ideally, thermoelectric generators should be made of the same material system to avoid thermal mismatch in the practical application. In this work, p-type Mg₃Sb_1.5Bi_0.5 which has almost the same composition as the state-of-the-art n-type Mg_3.2Sb_1.5Bi_0.49Te_0.01Mn_0.01 was synthesized by ball milling and spark plasma sintering, and then Na was chosen as an acceptor dopant to optimize the carrier concentration and further improve the thermoelectric performance. Na_0.0075Mg_2.9925Sb_1.5Bi_0.5 sample gets the highest ZT of ∼0.5 at 773 K. While Na_0.005Mg_2.995Sb_1.5Bi_0.5 sample shows the highest average ZT of ∼0.29 in the temperature range of 300–773 K and matched thermal expansion behavior with the state-of-the-art n-type Mg_3.2Sb_1.5Bi_0.49Te_0.01Mn_0.01, which is of great significance for practical applications. Taking the Joule and Thompson heat into account, a high theoretical conversion efficiency (η) of ∼9.5% was calculated for the thermoelectric module consists of the present p-type Na_0.005Mg_2.995Sb_1.5Bi_0.5 and the state-of-the-art n-type Mg_3.2Sb_1.5Bi_0.49Te_0.01Mn_0.01 with the leg length of 2 mm, and cold and hot side temperature of 300 K and 773 K, respectively, which shows a good potential for the use of this class of materials in the mid-temperature power generation applications.

近来，基于n型Mg ₃ Sb _1.5 Bi _0.5的热电材料因其非凡的热电性能而引起了相当大的关注。理想情况下，热电发电机应由相同的材料系统制成，以避免实际应用中的热失配。在这项工作中，p型Mg ₃ Sb _1.5 Bi _0.5的成分几乎与最新的n型Mg _3.2 Sb _1.5 Bi _0.49 Te _0.01 Mn _0.01通过球磨和火花等离子烧结合成碳纳米管，然后选择钠作为受体掺杂剂，以优化载流子浓度并进一步改善热电性能。Na _0.0075 Mg _2.9925 Sb _1.5 Bi _0.5样品在773 K时具有最高的ZT约_0.5。而Na _0.005 Mg _2.995 Sb _1.5 Bi _0.5样品在300–773 K的温度范围内具有相匹配的最高ZT约0.29。最先进的n型Mg _3.2 Sb _1.5 Bi _0.49 Te _0.01 Mn的热膨胀行为_0.01，对于实际应用具有重要意义。考虑到焦耳热和汤普森热，对于由目前的p型Na _0.005 Mg _2.995 Sb _1.5 Bi _0.5和当前状态的p型Na组成的热电模块，计算得出的理论转换效率（η）为9.5％。n型Mg _3.2 Sb _1.5 Bi _0.49 Te _0.01 Mn _0.01，腿长为2 mm，冷端和热端温度分别为300 K和773 K，这表明使用此类材料具有良好的潜力在中温发电应用中。